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A Quick Review of the Medical Physics Profession
Foreword
The modern practice of medicine relies heavily upon a significant number of physical tools, techniques and
principles of physical sciences. The complexity and precision required in the performance of the related
diagnostic and therapeutic procedures and the continued endeavours to further enhance these tools has led to
the development of the specialty of Medical Physics, which is primarily an applied branch of physics.
It is concerned with the application of the concepts and methods of physics to the diagnosis and treatment of
human disease. Medical Physicists interact with several specialities of medicine such as radiotherapy,
diagnostic and interventional radiology, nuclear medicine, cardiology, imaging procedures with Ultrasound and
Magnetic resonance, medical uses of infrared radiation, the use of lasers in medicine, etc.
Historical Review
Perhaps Leonardo do Vinci, six centuries ago, was the first medical physicist. Certainly it is true that he was
profoundly interested in the mechanics of the human locomotion. The subsequent gradual development of
physical tools contributed to advances in the biological sciences. One outstanding example is the microscope,
developed by the Dutch inventor, van Leeuwenhoek, during the 17th century. The development of the science
of electromagnetism in the 19th century enabled physicists to make contributions to medical treatment and
diagnosis. D’Arsonval, a French physicist, pioneered the therapeutic use of high-frequency electric currents
and pointed the way towards the development of electrical measuring instruments. Since then, sensitive
recording voltmeters, starting with the Einthoven string galvanometer, have made possible the development of
electrocardiography and electroencephalography.
The discoveries of x-rays and radioactivity by physicists, Roentgen in 1895 and Becquerel in 1896, were
rapidly followed by the application of ionising radiations to the diagnosis and treatment of disease. This use
has been primarily responsible for bringing physicists directly into the sphere of the hospital. In 1913, Duane
began work on radon sources for cancer treatment in a Boston Hospital and was followed in 1915 by Failla in
New York. In the 1920’s there was only a handful of physicists in medicine, but today, the number exceeds
20,000 worldwide.
The invention of powerful radiation sources to deliver interstitial and intra-cavitary radiation therapy, including
Van de Graaff generators, betatrons, cobalt-60 units, linear accelerators, microtrons and cyclotrons for
external beam radiation therapy; the application of man-made radionuclides to medical diagnosis and the
development of detection devices, such as the gamma cameras and positron emission tomography (PET)
scanners; the application of ionising radiation to medical diagnosis and the invention of imaging techniques
and devices, such as image intensifiers, computed tomography (CT), and digital radiology; and, more recently,
the utilisation of nuclear magnetic resonance (NMR) in medical imaging and spectroscopy have all created a
distinct role for medical physicists in the practice of the healing arts. Thus the growth and contribution of
medical physics is a natural consequence of the evolution of modern science and technology.
Therefore, issues concerning the use and dangers of ionising and non-ionising radiation, the Medical
Physicists, is the most suitable consultant. Is the scientist who can advise and inform correctly the public
around the problems of exposure to radiation as well as to disprove myths.
Areas of Activity
Medical physicist are concerned with three areas of activity:
 Clinical service and consultation
 Research and development
 Teaching.
On the average their time is distributed equally among these three areas.
Clinical Service
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Medical Physicists are heavily involved in areas of diagnosis and treatment, often with specific patients. These
activities take the form of consultations with physician colleagues. The hospitals departments, where the
presence of Medical Physicists is essential and continuous are (a) Radiotherapy (b) Nuclear Medicine, and (c)
Radiology departments.
In Radiotherapy departments, among the duties and responsibilities of the Medical Physicist, is the planning of
radiation treatments for cancer patients, using either external radiation beams or internal radioactive sources.
An indispensable service is the accurate measurement of the radiation output from radiation sources
employed in cancer therapy. In the specialty of nuclear medicine, medical physicists collaborate with
physicians in procedures utilising radionuclides for delineating internal organs and determining important
physiological variables, such as metabolic rates and blood flow. Other important services are rendered through
investigation of equipment performance, organisation of quality control in imaging systems, design of radiation
installations, and control of radiation hazards.
The medical physicist is called upon to contribute clinical and scientific advice and resources to solve the
numerous and diverse physical problems that arise continually in many specialised medical areas.
Research
Medical physicists play a vital and often leading role within the medical research team. Their activities cover
wide frontiers, including such key areas as cancer, heart disease and mental illness. In cancer, they work
primarily on radiation problems, such as the basic mechanisms of biological change after irradiation, the
application of new high-energy machines to patient treatment and the development of new techniques for
precise measurement of radiation. Significant computer developments continue in the area of dose calculation
for patient treatment and video display of this treatment information. Particle irradiation is an area of active
research with promising biological advantages over traditional photon treatments. In heart disease, medical
physicists work on the measurement of blood flow and oxygenation. In mental illness, they work on the
recording, correlation and interpretation of bioelectric potentials.
Medical physicists are also concerned with research of general medical significance, including the application
of computers in medicine and applications of information theory to diagnostic problems; processing, storing
and retrieving medical images; measuring the amount of radioactivity in the human body and foodstuffs; and
studying the anatomical and temporal distribution of radioactive substances in the body.
Medical physicists are also involved in the development of new instrumentation and technology for use in
diagnostic radiology. These include the use of magnetic and electro-optical storage devices for the
manipulation of x-ray images, quantitative analysis of both static and dynamic images using computer
techniques, radiation methods for the analysis of tissue characteristics and composition, and the exciting new
areas of computerised tomography and magnetic resonance imaging for displaying detailed cross-sectional
images of the anatomy. Medical physicists are also engaged in research and development on imaging
procedures utilising infrared and ultrasound sources. Typical examples of the various research areas presently
under active investigation may be found in scientific journals dedicated to the field.
Teaching
Often Medical Physicists are employed in higher educational establishments, where they help train future
medical physicists, resident physicians, medical students, radiographic technologists and nurses. They also
conduct courses in medical physics and aspects of biophysics and radiobiology for a variety of graduate and
postgraduate programmes.
Teaching is a part of the Medical Physicists tasks within hospitals. The continuing education of medical and
paramedical personnel in matters of radiation protection is the responsibility of the Medical Physicist.
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Professional Position
Medical Physicist are usually employed in hospital and other medical care facilities, university hospitals and
other Higher education institutions. In many hospitals, medical physicists hold professional appointments in
one of the clinical departments, frequently the radiology department and are members of the professional staff
of the hospital. Some of the larger hospitals have considerably more medical physicists organised into medical
physics departments.
Medical Physicists cooperate with a wide range of health professionals. Other than the medical and
paramedical staff, they often collaborate with engineers and administrative staff to design new equipment and
for upgrading techniques and procedures that serve diagnosis and therapy.
As consultants and researchers, medical physicists are held in high regard by the medical profession. In
addition to their university and/or hospital appointments, many medical physicists have professional consulting
activities outside of their primary employment.
Training of the Medical Physicist
Several universities offer academic programmes in medical physics leading to a master’s or doctoral degree. A
thorough preparation in general physics is highly desirable before entry into these programmes. The most
common programmes emphasise the physical properties and medical applications of radiations of all types.
Academic training alone does not make a medical physicist. Practical experience with medical problems is
essential. This experience may be acquired through a residency traineeship or postdoctoral program of one or
two years in a hospital. These latter programmes are an important mode of entry into the profession.
Demand for medical physicists
Medical physics is a profession in which there is a steadily growing demand for trained individuals. Most large
medical centres now employ medical physicists and many smaller hospitals are seeking well-trained medical
physicists. The manpower needs are expected to grow on average of about 5% per year on a global scale.
While radiation therapy continues to be the major field of employment for medical physicists, new
developments and greater sophistication in equipment and procedures for diagnostic radiology and nuclear
medicine have brought about a substantial increase in positions available in these two fields.
The future
Many forces are working to make medical physics a creative, expanding and rewarding profession for the
young scientist about to choose a career. A characteristic of our society is its ever-increasing pre-occupation
with health.
Recent technical advances in health care are increasingly available to all persons. Health care now accounts
for around 10% of the gross national product of most nations. The research attack on cancer and heart
disease is growing yearly. New methods of diagnosis and therapy, are being developed and applied. These
methods increasingly demand the special skills of medical physicists not only in research, but also in the
application of patient care. Even though the mood today seems to favour emphasis on general practice, it is
difficult to see how the human aspiration and endeavours to diagnose and treat human diseases as precisely
and as timely as possible, can be curtailed.
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